Conventional flap deployment systems include flap track mechanisms, drop link mechanisms, and multi-bar linkage mechanisms. Flap track mechanisms employ a track on which the flap runs on roller bearings as it moves between its retracted and extended positions. Drop link mechanisms employ a rigid drop link which is pivotally coupled at one end to the main wing element and to the flap at the other end.
Most flap deployment systems impart a vertical rotation to the flap so as to increase the camber of the wing. Some also impart a degree of rearward translation to the flap (commonly referred to as “Fowler motion”). US 2007/0034748 A1 discloses a multi-bar linkage mechanism which imparts a degree of horizontal rotation to the flap. This has the effect of increasing the degree of sweep of the wing in the region of the flap.
A degree of sweep in the trailing edge of the wing may be desirable to reduce drag during high speed operations, but may be less than optimal for low speed operations in which a higher lift coefficient is required.
U.S. Pat. No. 4,172,575 discloses a flap deployment system in which inboard and outboard flap linkage mechanisms act together to produce a pseudo conical flap extension. Both linkages are driven from a single rotary actuator.